shiftNode/shiftNode.cpp

//-
// ==========================================================================
// Copyright 1995,2006,2008 Autodesk, Inc. All rights reserved.
//
// Use of this software is subject to the terms of the Autodesk
// license agreement provided at the time of installation or download,
// or which otherwise accompanies this software in either electronic
// or hard copy form.
// ==========================================================================
//+

// DESCRIPTION:
// 
// Produces the dependency graph node "shiftNode".
//
// This plug-in demonstrates modifying uvCoord and refPointCamera from within a
// texture plug-in. The uvCoord and refPointCamera are marked as "renderSource" attributes.
// The uvCoord and refPointCamera for the current sample position are requested
// and then subsequently shifted four times. Each time these attributes are modified,
// the inColor attribute is requested, and because the attributes are render sources,
// the request for inColor forces a shading evaluation. Thus, the 2D or 3D texture
// connected to inColor will be evaluated four additional times for every point shaded.
// The inColor values are averaged which produces a blurred result. 
//

#include <maya/MFnPlugin.h>
#include <maya/MPxNode.h>
#include <maya/MString.h>
#include <maya/MTypeId.h>
#include <maya/MPlug.h>
#include <maya/MDataBlock.h>
#include <maya/MDataHandle.h> 
#include <maya/MFnNumericAttribute.h>
#include <maya/MFloatVector.h>


// Error macro: if not successful, print error message and return
// the MStatus instance containing the error code.
// Assumes that "stat" contains the error value
#define PERRORfail(stat,msg) \
    if (!(stat)) { stat.perror((msg)); return (stat); }


// Forward Declarations //

class shiftNode;

// Plugin Lambert Shader Class //

class shiftNode : public MPxNode
{
    public: // Methods
    shiftNode();
    ~shiftNode() override;
    
    MStatus compute( const MPlug&, MDataBlock& ) override;
    
    static  void *          creator();
    static  MStatus         initialize();

    //  Id tag for use with binary file format
    static MTypeId id;

    private:

    float ox, oy, oz;
    int initID, doneID;
    static bool firstTime;

    // Input
    static MObject aShift;
    static MObject aDist;

    static MObject aColor;

    static MObject aRefPointCamera;
    static MObject aUv;

    // Output
    static MObject aOutColor;

};


// attribute information

MTypeId shiftNode::id( 0x8001a );

// input

MObject     shiftNode::aShift;
MObject     shiftNode::aDist;
MObject     shiftNode::aColor;
MObject     shiftNode::aRefPointCamera;
MObject     shiftNode::aUv;

// output

MObject     shiftNode::aOutColor;

shiftNode::shiftNode()
{
}

shiftNode::~shiftNode()
{
}

// creates an instance of the node
void * shiftNode::creator()
{
    return new shiftNode();
}

// initializes attribute information
MStatus shiftNode::initialize()
{
    MStatus stat;

    MFnNumericAttribute nAttr; 

    // shift

    aShift = nAttr.create( "shift", "sh", 
                          MFnNumericData::kBoolean, false );
    stat = addAttribute( aShift );
    PERRORfail( stat, "addAttribute shift" );

    // distance

    aDist = nAttr.create( "distance", "dis", 
                         MFnNumericData::kFloat, 0.0 );
    stat = addAttribute( aDist );
    PERRORfail( stat, "addAttribute dist" );

    // inColor

    aColor = nAttr.createColor( "color", "c" );
    nAttr.setStorable(false);
    stat = addAttribute( aColor );
    PERRORfail( stat, "addAttribute inColor" );
    
    // refPointCamera

    aRefPointCamera = nAttr.createPoint( "refPointCamera", "rpc" );
    nAttr.setStorable(false);
    nAttr.setWritable(true);
    nAttr.setRenderSource(true);
    nAttr.setHidden(true);
    stat = addAttribute( aRefPointCamera );
    PERRORfail( stat, "addAttribute refPointCamera" );

    // uv

    MObject u = nAttr.create( "uCoord", "u", MFnNumericData::kFloat, 0.0 );
    MObject v = nAttr.create( "vCoord", "v", MFnNumericData::kFloat, 0.0 );
    aUv = nAttr.create( "uvCoord", "uv", u, v );
    nAttr.setStorable(false);
    nAttr.setWritable(true);
    nAttr.setRenderSource(true);
    nAttr.setHidden(true);
    stat = addAttribute( aUv );
    PERRORfail( stat, "addAttribute uv" );

    // create output attributes here

    aOutColor = nAttr.createColor( "outColor", "oc" );
    PERRORfail(stat, "initialize create outColor attribute");
    nAttr.setReadable( true );
    nAttr.setWritable( false );
    stat = addAttribute( aOutColor );
    PERRORfail(stat, "addAttribute(outColor)");
    
    // attribute affects

    attributeAffects ( aShift, aOutColor );
    attributeAffects ( aDist, aOutColor );
    attributeAffects ( aColor, aOutColor );
    attributeAffects ( aRefPointCamera, aOutColor );
    attributeAffects ( aUv, aOutColor );

    // we need to do the followings to cause other input attributes
    // to evaluate with the new values we set

    attributeAffects ( aUv, aUv );
    attributeAffects ( aRefPointCamera, aRefPointCamera );

    return MS::kSuccess;
}


/*

This function gets called by Maya to evaluate the texture.

*/
MStatus shiftNode::compute( const MPlug& plug, MDataBlock& data ) 
{
    MStatus stat;

    if ((plug != aOutColor) && (plug.parent() != aOutColor))
        return MS::kUnknownParameter;

    MDataHandle colorH;
    MFloatVector color;

    MDataHandle shiftH = data.inputValue( aShift, &stat);
    PERRORfail(stat, "compute getting shift attr");
    bool shiftIt = shiftH.asBool();

    MDataHandle distH = data.inputValue( aDist, &stat);
    PERRORfail(stat, "compute getting distance attr");
    float distance = distH.asFloat();

    MFloatVector clr;

    if ( shiftIt && distance != 0.0 )
    {
        // first evaluate color at default sample posiiton

        clr = data.inputValue( aColor ).asFloatVector();

        // uv is used by 2d textures
        // refPointCamera is used by 3d textures

        MDataHandle refPointCamH = data.inputValue( aRefPointCamera, &stat);
        PERRORfail(stat, "compute getting refPointCamera attr");
        MFloatVector refPC = refPointCamH.asFloatVector();

        // get current UV

        const float2 & oldUV = data.inputValue(aUv).asFloat2();

        // shift and set the uv/refPointCamera values so
        // we can sample around the current uv/refPointCamera

        MDataHandle outUV = data.outputValue( aUv );
        MDataHandle outPC = data.outputValue( aRefPointCamera );

        outUV.set( oldUV[0]-distance, oldUV[1] );
        outPC.set( refPC.x + distance, refPC.y + distance, refPC.z + distance);
        colorH = data.inputValue( aColor, &stat);   // evaluate at new pos
        color = colorH.asFloatVector();
        clr += color;

        outUV.set( oldUV[0]+distance, oldUV[1] );
        outPC.set( refPC.x - distance, refPC.y + distance, refPC.z + distance);
        colorH = data.inputValue( aColor, &stat);   // evaluate at new pos
        color = colorH.asFloatVector();
        clr += color;

        outUV.set( oldUV[0], oldUV[1]-distance );
        outPC.set( refPC.x + distance, refPC.y - distance, refPC.z + distance);
        colorH = data.inputValue( aColor, &stat);   // evaluate at new pos
        color = colorH.asFloatVector();
        clr += color;

        outUV.set( oldUV[0], oldUV[1]+distance );
        outPC.set( refPC.x - distance, refPC.y - distance, refPC.z + distance);
        colorH = data.inputValue( aColor, &stat);   // evaluate at new pos
        color = colorH.asFloatVector();
        clr += color;

        clr /= 5.0; // average the colors from all locations

        // set sample data back to original values

        outUV.set( oldUV[0], oldUV[1] );
        outPC.set( refPC.x, refPC.y, refPC.z ); 
    }
    else
    {
        colorH = data.inputValue( aColor, &stat);
        clr = colorH.asFloatVector();
    }

    MDataHandle outColorHandle = data.outputValue( aOutColor );
    MFloatVector& oclr = outColorHandle.asFloatVector();
    oclr = clr;
    outColorHandle.setClean();

    return MS::kSuccess;
}


//
//
//

MStatus initializePlugin( MObject obj )
{
   const MString UserClassify( "utility/general" );

    MFnPlugin plugin( obj, PLUGIN_COMPANY, "4.5", "Any");
    plugin.registerNode( "shiftNode", shiftNode::id,
                         shiftNode::creator, shiftNode::initialize,
                         MPxNode::kDependNode, &UserClassify );

   return MS::kSuccess;

}

MStatus uninitializePlugin( MObject obj )
{
    MFnPlugin plugin( obj );
    plugin.deregisterNode( shiftNode::id );

    return MS::kSuccess;
}